The recent lumber trade war between Canada and the United States deals with Canadian stumpage policies, Canada’s log export controls, and U.S. retaliatory duty. This study determines the appropriate level of U.S. countervailing duty (CVD) by employing a vertically interrelated log–lumber model. The theoretical results show that the U.S. CVD can be greater (will be less) than the Canadian subsidy for a vertically related log–lumbermarket (for lumber market only). Empirical results support the theoretical findings in that the U.S. CVD for the log–lumber market (lumber market alone) is 1.55 (0.91) times the Canadian subsidy.